break up velero-builder stage to allow more concurrent layer builds.

Signed-off-by: Tiger Kaovilai <[email protected]>

Dockerfile

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 # Velero binary build section
-FROM --platform=$BUILDPLATFORM golang:1.22-bookworm AS velero-builder
+FROM --platform=$BUILDPLATFORM golang:1.22-bookworm AS velero-builder-base
 
 ARG GOPROXY
 ARG BIN
@@ -41,13 +41,15 @@ RUN go mod download
 
 COPY . /go/src/github.com/vmware-tanzu/velero
 
-RUN mkdir -p /output/usr/bin && \
-    export GOARM=$( echo "${GOARM}" | cut -c2-) && \
-    go build -o /output/${BIN} \
-    -ldflags "${LDFLAGS}" ${PKG}/cmd/${BIN} && \
-    go build -o /output/velero-helper \
-    -ldflags "${LDFLAGS}" ${PKG}/cmd/velero-helper && \
-    go clean -modcache -cache
+RUN mkdir -p /output/usr/bin
+
+FROM velero-builder-base AS velero-builder-helper
+RUN GOARM=$( echo "${GOARM}" | cut -c2-) go build -o /output/velero-helper \
+-ldflags "${LDFLAGS}" ${PKG}/cmd/velero-helper
+
+FROM velero-builder-base AS velero-builder
+RUN GOARM=$( echo "${GOARM}" | cut -c2-) go build -o /output/${BIN} \
+    -ldflags "${LDFLAGS}" ${PKG}/cmd/${BIN}
 
 # Restic binary build section
 FROM --platform=$BUILDPLATFORM golang:1.22-bookworm AS restic-builder
@@ -66,6 +68,9 @@ ENV CGO_ENABLED=0 \
     GOARCH=${TARGETARCH} \
     GOARM=${TARGETVARIANT}
 
+# /output dir needed by last stage to copy even when BIN is not velero
+RUN mkdir -p /output/usr/bin
+
 # cache go mod download before applying patches
 RUN --mount=type=cache,target=/go/pkg/mod if [ "${BIN}" = "velero" ]; then \
         mkdir -p /build/restic && \
@@ -79,7 +84,6 @@ COPY hack/fix_restic_cve.txt /go/src/github.com/vmware-tanzu/velero/hack/
 
 # cache go mod download after applying patches
 RUN --mount=type=cache,target=/go/pkg/mod if [ "${BIN}" = "velero" ]; then \
-        mkdir -p /output/usr/bin && \        
         cd /build/restic && \
         git apply /go/src/github.com/vmware-tanzu/velero/hack/fix_restic_cve.txt && \
         go mod download; \
@@ -99,6 +103,8 @@ LABEL maintainer="Xun Jiang <[email protected]>"
 
 COPY --from=velero-builder /output /
 
+COPY --from=velero-builder-helper /output /
+
 COPY --from=restic-builder /output /
 
 USER cnb:cnb